The studies will consider five aspects of the mode of action and metabolism of organic toxicants with emphasis on pest control agents and the definition of safe and efficient conditions for their use. Investigations on synthetic pyrethroids will include metabolism studies in mammals, insects, plants and enzyme systems, photodecomposition, synthesis of metabolites and photoproducts, and spectroscopy and analysis. Compounds to be investigated are permethrin, NRDC 161 and others of potential use in agricultural pest insect control. In examing toxaphene, priority will be given to preparation of adequate amounts of toxaphene components for critical studies on their degradation chemistry and toxicology. Research will continue on the chemistry, metabolism, mode of action and toxicology of the acaricidal and fungicidal alkyltin derivatives and their hydroxyalkyltin metabolites. The studies on organophosphorus and methylcarbamate pesticides will emphasize non-cholinergic effects including teratogenesis, delayed neurotoxicity and compounds that block GABA receptors in the central nervous system. The interaction of thiocarbamate herbicides and their dichloroacetamide antidotes are to be investigated in both plants and mammals focusing on the glutathione and glutathione S-transferase system. Research will also continue on the mode of action of dimilin in blocking chitin synthesis in insects. The general approach involves the combined techniques of toxicology, organic chemistry, analytical chemistry, radiochemistry and biochemistry to define the effects of the toxicant on the organism and of the organism on the pesticide or related toxicant. BIBLIOGRAPHIC REFERENCES: Ellicott, M., J.E. Janes, D.A. Alman, L.C. Gaughan, T. Unai and J.E. Casida. 1976. Radiosynthesis and metabolism in rats of the (1R) isomers of the insecticide permethrin. J. Agr. Food Chem. 24:270-276. Proctor, N.H., A.D. Moscioni and J.E. Casida. 1976. Chicken embryo NAD levels lowered by teratogenic organophosphorus and methylcarbamate insecticides. Biochem. Pharmacol., 25: 757-762.